How do Korsakoff patients learn new concepts?

The goal of the present investigation was to assess semantic learning in Korsakoff patients (KS), compared with uncomplicated alcoholics (AL) and control subjects (CS), taking the nature of the information to-be-learned and the episodic memory profiles of the three groups into account. Ten new complex concepts, each illustrated by a photo and composed of a label, a category and three features, were taught to 13 KS, 23 AL and 45 CS. When examined independently of the main experimental task, the two patients' groups presented episodic memory, working memory and executive impairments but episodic memory was more severely impaired in KS. Both AL and KS exhibited label learning deficits but KS were more severely impaired than AL. The episodic memory results were the main factor accounting for label learning performance when the three groups were pooled together. When examined within each group, the correlation was significant in CS and AL but not in KS. Only KS exhibited impaired category and feature learning results. Episodic memory did not account for category and feature learning performance. New label learning may be equivalent to that of proper names, requiring the involvement of episodic memory notably to arbitrarily associate a meaningless word with a specific identity. However, when episodic memory is severely impaired like in KS, an alternative neocortical learning route, bypassing episodic memory, may be invoked. Category and feature seem to be acquired independently of episodic memory. The specific impairment in category and feature learning in KS may therefore reflect a genuine deficit of semantic memory in Korsakoff's syndrome.